Method of making core box vent plugs



Feb. 23, 1954 E. F. PETERSON 2,669,769

METHOD OF MAKING CORE BOX VENT PLUGS Filed Sept. 10, 1949 2 Sheets-Sheet 1 INVENTOR. 25 mwdrz FPsZi'erspn ZJJLJE Feb. 23, 1954 PETERSON 2,669,769

METHOD OF MAKING CORE BOX VENT PLUGS Filed Sept. 10, 1949 2 Sheets-Sheet 2 INVENTOR. Evin F. Pezi'enso /z/ Patented Feb. 23, 1954 METHOD OF MAKING CORE BOX VENT PLUGS Edwin F. Peterson, Kewanee, Ill.

Application September 10, 1949, Serial No. 115,031

1 Claim.

This invention is directed to a core box vent plug and the method of making such plugs each of which comprises a cupped metal or plastic unit having a sleeve portion for seating in a core box vent and having a perforated thick base to bleed air from the core box interior and to provide an auxiliary surface to span the vent area to thus suitably complete the core box surface areas at each vent.

In using vent plugs it is general practice to provide numerous vents and plugs in core boxes in positions calculated to do the most good in the most efficient manner to obtain well made finished cores. A blast of air borne core sand into a core box must have quick dissipation of the air plus entrapment of the sand. This action is best obtained by placing numerous vents in well selected positions to encourage the complete filling of the core box. And such vents must be capable of allowing air to escape and to retain the sand by the use of vent plugs secured therein.

The vents are kept small in diameter and the plugs likewise range small, for example, from of an inch or under in diameter. This restricted size makes it difiicult to fabricate plugs accurately and in quantity.

It is one of the main objects of this invention to produce these small plugs from metal and to so design the same as to lend themselves to accurate and large quantity production. Y

One of the further objects of this invention is to provide a core box vent plug that is uniform and of sturdy structural material adapted to hold its shape while performing its function, and one that will not blemish or distort the surface of the finished core. It has been found that screen vents, which are now in general use for this purpose, have a tendency to dish under normal core making conditions requiring manual touching up of the cores removed from the core boxes which is objectionable and costly.

Another object of the present invention is to provide a simple method to inexpensively produce vent plugs from pellets cut from a rod of predetermined diameter or punched from plate or sheet stock. The method of makingincludes a variation wherein the plugs may be made directly from rod stock instead of pellets.

Another feature of the invention is to provide a plug wherein the sleeve is tapered to help hold the plugs in place within the core box vents while being subjected to the internal pressure in the box during the core making stage.

The plug is provided with a semi-flexible thin shell to conform to the surface of the core box 2 vent opening and to adjust itself to any irregularities in the vent structure. The plug then has a heavy transverse base to reenforce the shell at the adjacent base end and to keep the shell from.

collapsing making this end of the plug sturdy and capable of withstanding the radially inwardly directed stresses induced by forcing the plug home in the core box vent. This relationship of the vent plug base and sleeve together with the enlarged peripheral portion of the plug at the base all contribute to the efiicient and eifective use of the plug in its designed capacity.

The heavy base not only forms a stiff wall for the core box at the vent opening but also provides a solid end for receiving blows from any tool that may be used in driving the plug into place in the core box vent with the surface of the base flush with the interior surface of the core box chamber.

The core box vent plug further includes the idea of using tapered apertures in the plug base or bottom with the same widening out in the direction away from the internal surface contour of the core box so that no sand or other foreign matter which may enter the openings will become lodged therein. The apertures are selfcleaning by virtue of the tapering walls thereof. In this same category it is proposed to use variously shaped and arranged openings in the face of the plug having selected minimum widths or diameters as best determined by the caliper or grade of sand or other material used in making cores.

As another feature of the invention it is possible to vary such minimum widths or diameters of the entry or face portions of the vent plug apertures by selection with the proper positioning of the cut-off plane in transverse relation to the length of the stock penetration of the openings as initially formed in the metal stock used to make the plugs with the method herein proposed.

This plug and method of making same also contemplates the introduction of reenforcing ribs within the small interior cavity of the plug. The

ribs are axially disposed between the base and the sleeve walls and positioned radially within the hollow of the vent plug. Thus the ribs tie the sleeve and base together to strengthen the base against deformation and the sleeve against collapse.

In a small bore vent plug of this kind made by the method herein proposed it is possible to introduce suitably positioned ribs or fins to produce a light weight cellular structure with a thinner base or thinner walled sleeve, or both, to

sustain the internal core filling air and sand pressures. Thin plugs of this character with selected perforated base patterns can be manufactured with rapidity and ease by the present method and will serve their designed purposes with efiicieney under long periods of use.

Under the impact method used to manufacture the vent plugs it is a further object to select base aperture patterns that will permit radial displacement of thepellet metal under the forming ram impact to create a complete and flawless vent plug. The designs of apertured bases illustrated have proven satisfactory in that they provide suhicient avenues for radial displacement of the metal to flow about the forming ram parts and into the sleeve cavity under impact without injury or damage to such ram parts. The designs are suggestive only and may be varied but they do fulfill the operative fabrication requirements.

Other features and advantages of the vent plu of this invention and the method of making the same shall hereinafter appear in the following detailed description having reference to the accompanying drawings forming .a part of this Specification.

In the drawings:

Fig. 1 is a fragmentary .cross sectional .view of a portion of a core box taken through a core box vent with the plug of the present invention seated within such vent and in section substantially as viewed along the line l-l in Fig. 2;

Fig. 2 is a face view of a fragmentary wall portion of a core box with the exposed face of the vent plug shown flush with the surface of the core box at the vent area location thereof;

Fig. 3 is a perspective view of a pellet used as the stock piece from which a plug is .to be fabris cated;

Fig. 4 shows a cross sectional view of a fragmentary portion of a die used in the formation of the plug with one of the pellets in place;

Fig. 5 is another cross sectional view of the die with further structural details and illustrating the first step of pellet deformation by impact to produce the vent plug;

Fig. 6 indicates the trimming step to level oil the skirt or sleeve portion of the plug to produce a plug of given length;

Fig. '7 illustrates another step in the method of making the plug to produce the tapered end; this step being optional although preferred;

Fig. '8 shows the last step in making the plug which is also a cut-off or trimming stage for completing the plug to final length and to open the plurality of preformed apertures in the plug;

Fig. 9 is a side View of a fragmentary part of a piece or rod stock that may be used in a modified manner to fabricate vent plugs of the present design;

Fig. 10 shows the same rod stock partially in section and drilled axially as the first step of this modified way of making vent plugs;

Fig. 11 illustrates a hoblclil'is operation to deform the rod stock by penetration at which state the plug parallels the Fig. 5 step shown in the I first method illustrated;

Fig. 12 indicates the cut-off step which protherein as this portion of the plug appears when made by the hobbing process;

Fig. 14, is a similar View as Fig. 1.3, but prior to; the cut-off state to indicate how the entry di ameter of the openings might be varied by a shift in the transverse cutting plane selected;

Figure 15 is an inside view of the plug shown in Fig. 1 as the same would appear when seen from the left in Fig. l and removed from the core box;

Figs. 16 and 17 are face views of vent plugs illustrating different feasible aperture patterns of air bleed openings arranged for fabrication by the methods indicated and as hereinafter described;

Fig. 18 is an inside view of a vent plug of light weight design including diametric ribs connected and extending between the sleeve walls and across said apertured base; and

19:35 .a detailed sectional View of the latter plug as seen substantially along the line le-i 8 in As best seen in Figs. 1 and 2, the vent plug I is lodged in fixed position within a bore 2 in a Wall -3 of a core box 4, and comprises a thin sleeve 5 having a closed end forming a heavy base 6 which is the closure Wall of the plug, with the base 6 having a plurality of tapered apertures 1 therein to bleed air from the chamber 8 of the core box 4 into the sleeve 5, bore 2 and out into the atmosphere.

As will be explained in the method of making the plug, the base diameter is preferably somewhat greater than the diameter of the open end of the sleeve to aid in holding the plug firmly seated Within bore .2 of the core box 4 thus counteracting displacement of the plug under internal core box pressures created during the core mak ing cycle. bore area and should at all times remain flush with the inner surface ll) of the wall 3 of the core box 4 to produce sand cores in the box that Will come out finished and complete in spite of the vent area existing at the vent plug location.

The apertures 1 are divergently tapered inwardly from the face 9 of the plug 1 to widen into the hollow interior of the sleeve 5 by which arrangement the apertures are self-cleaning to remain fully open and to function intheir full capacity for venting the interior chamber of the core box 4.

As an added feature the cavity of the plug l is provided with radially positioned fins or ribs 5a that extend axially from the base 6 toward the open end of the sleeve 5. These ribs ta provide reenforcing structure between the base 6 and the sleeve 5 to introduce optimum rigidity and strength into a vent plug of this character as made possible by reason of the impact method employed in making these plugs.

The method of making this vent plug is illustrated in Figs. 3 to 8 inclusive and will be referred to as the impact method. As the stock, pellets such as H are punched from plate or sheet stock material such as aluminum, or they may be cut or sheared from rod stock if desired. Each pellet H is then dropped into a bore ii. in a die l3 as shown in Fig. 4, the bore terminating in a. shallow conical or dipped bottom M. which aids flow and distribution of the pelletmetal mass under impact and which also forms shape of the-finished; vent-plugbytheimpact of a ranr 1-6 having prongs l'l at-the end thereof t p etretejt e a o io f the s o -f rm- The face 9 of the plug l spans the.

a pattern of predetemiined open design in the bottom of theplugr Ram; Wis alsoappropriately slotted. at Ila to provide the. forming means for the'r'ibs 5a. Obviously, this impact step may be divided into a general initial forming step. to-.merel'yprovide the sleeve shape. followed by an impact step to subsequently, form the hole. penetrations in the base portion of the plug. if. this dual procedure is desired.

The plug 1 formed in Fig. 5 is then removed; from the impact ram It by a stripper it during. retraction of the ram after which. the sequence. of this forming stage is repeated. When the. plugis formed in Fig. 5 it has a wavy free upper edge 19' on sleeve 5' which. is thentrimmed. oft along. aline. by cutting or grinding means. 2 I; as seen in Fig. 6'.

Fig. 7 indicates the step in the process of making these plugs wherein a suitably shaped holding die 2?. positions the plug for contact by a ram 23 forced against the surface tip l5 of the plug I. This action tends to flatten tip [5 and cause radial expansion of the bottom 6 of the plug l as at 24 to attain a larger tapered end on'the plug in a position about the base 5 and partially along sleeve 5 to produce a tight fitting plug that will counteract rotational or axial movement within the core box vent having the plug therein. With the sleeve diameter smaller better plug insertion is possible when they are being forced into place in core box vent bores. The surface tip is is a convenient way to supply excess base metal for the upsetting operation. By squeezing a base formed with coplanar surfaces between two compression members as in Fig. 7, a similar radial base expansion may be obtained. Also, by tapering the end of the ram 23 to simulate the tip I5, a coplanar surfaced base can also be expanded.

The final plug trimming stage is indicated in Fig. 8 wherein a slice is taken off of the plug I along a transverse plane by a cutting or grinding means 26. Obviously it is possible to double trim the plug l simultaneously to perform both the Figs. 6 and 8 operations if the Fig. 7 step is not used and in close tolerance situations may warrant such procedure.

It should be noted that the hereinbefore described expanding step is performed before the base slots or penetrations are exposed by removing a portion from the outer surface of the base. In the modified method to follow the expandable action is also employed before the solid portion of the base is removed from the opening design that has been impressed into the body of the base. This prevents distortion of the openings and the surrounding portions of the plug to thus maintain the designed maximum or minimum clearances of the structure at the exposed finished surface of the plug. And, by using a thick headed plug, no distortion between the patterned plug face parts results when the plug is driven home in a core box vent to accomplish its purpose.

This modified procedure is shown in Figs. 9 to 12 inclusive and contemplates using a round stock rod 2'5 of a selected material such as aluminum. This rod 2! is axially drilled as 23 to a given depth and then retained in a fixed position by a clamp 29 whereupon a hobbing tool 30 is driven into the bore 28 and forced into the rod metal a predetermined amount. Tool an has a plurality of tapered prongs 3| of a given arrangement to penetrate the rod, this action automatically causing the rod to swell radially out- 6 wavdly at the radial? plane of the prongs to pro-- duos-the tapered plug" without the Fig: 7 tunetion. A- piece of the nod'z lis then-cut off alongthe plane of theline' 32- traversing the holes 7* to fornr thefinished plug i. As seen in Fig. r4;

by changing-the cutting plane to any one ofa number of positions 33, 3-4; or 3*, the size of the finished openings on the face side of the finished plug shall be as at as, 3 1 and 33 respectively.

The hobbin-g operation also produces a slight swell" at the inner"plug outlet ends of the apertures or openings 1- to create by metal flow an annular ridge 39 which will" reenforce the larger peripheral outlet areas about the-holes or openings in baseii-for addedstrength to counteract cracking or fissu-ring leading to rupture between adjacent. opemngs. use. Ridges 39 also permit the use of a thinner base 6 in the manufaoture of the plugs I. Hobbing tool 38 may also include rib forming recesses, if desirable, to produce ribs such as 5a in Fig. 1.

In the vent plug I shown in the previous figures, the openings 1 constitute a plurality of interrupted concentric slots as shown in Fig. 2. In Fig. 16 and 17 other vent opening arrangements are shown. In Fig. 16, a radial design of slots 40 are indicated. Fig. 17 shows another concentric slot aperture design 4|. Fig. 18 is made with a quarterly slotted pattern having the generally radially disposed slots 43 in the four segments of the plug. Each of these patterns are arranged with avenues providing for proper radial displacement of the metal under ram impact, the avenue being generally radially located to protect the ram parts when in operation.

In all the designs the maximum diameter of the holes or the maximum width of the slots must be selected in accordance with the coarse ness or fineness of the sand used in the making of cores in the core box. By tapering all the openings divergingly away from the face side 9 of the plug, the same variable cutting plane procedure explained with reference to Fig. 14 may be followed to determine the maximum face sizes of the openings of the vent plug apertures.

For example, when sand is used wherein the greater percentage of the granules thereof exceed 0.016 of an inch making this the maximum fineness, the maximum width of the slots or diameters of the holes may be retained at approximately 0.014 of an inch. This practice would allow retention of the core sand in the core box and also provide for passage of smaller grains or of dirt and other foreign matter that would find its way to the vent plug areas.

Figs. 18 and 19 show a plug 44 having diametric ribs or fins 45 disposed within the plug cavity to illustrate the idea of using such ribs to create a cellular plug. Such a plug is of great strength and would allow the use of a, very thin sleeve 46 and a very thin base 4'! with suitable apertures such as 13 hereinbefore noted. And a plug of this type can be readily produced by the methods herein disclosed and explained.

All contemplated variations, changes or modifications in the vent plug per se or in the method of making the same shall be governed by the breadth and scope of the appended claim directed to the subject matter of the present invention.

What I claim is:

l The method of making a core box vent plug comprising an integral one piece body in the form of a cup, said cup having a perforated heavy base and a contiguous thin walled portion 'extending away from said base; which method consists of placing a stock pellet within a confining cavity of a die, striking said pellet with impact means to deform said pellet into a thin walled cup with a thick base; "and simultaneously causing partial perforation of said base from within said cup, then trimming the open end wall portions of said cup to a predetermined length, then applying pressure to opposite sides of the thick base to produce limited radial expansion of said cup at the base end thereof with respectto the cup wall end thereof, and finally removing a complete transverse portion of the external surface of the base to expose the ad jacent ends of the partial base perforations.

EDWIN F. PETERSON.

References Cited in the file of this patent UNITED's' rA'rEs PATENTS Number Date Name Carlson Aug. 17, 1915 Talty, Jan. 10, 1922 McEvory Jan. 22, 1929 Barker Apr. 15, 1930 Gibson Sept. 1, 1931 Weatherhead Jan. 5, 1932 Rigby Jan. 19, 1932 Cornell Feb. 14, .1939 Hixon May 2, 1939 Wempe May 22, 1945 Hungate Aug. 2, 1949 Copeland Sept. 20, 1949 Dudzinski Sept. 20, 1949 

